Caption: Aortic aneurysm, 2D (left) and coloured 3D (right) sagittal computed tomography (CT) scans. 58-year-old man with an extended aneurysm (thick, light grey tube) of the aorta from the sigmoid valve to the iliac junction. The front of the body is at left and the head is at top. An aortic aneurysm is a swelling of the aorta, usually due to an underlying weakness in the wall of the artery. This may lead to rupture, causing severe pain, massive internal haemorrhage (bleeding), and, if left untreated, death.